1. Field of the Invention
The present invention relates to structures used to support growing crops, and more particularly to the combination of an improved cross arm and bent trellis support member for use in a trellis structure to support vine borne crops.
2. Description of the Prior Art
Various trellis structures are widely used in the training and support of commercial crops. A typical commercial agricultural grape vineyard is made up of a plurality of parallel rows of growing plants. In order to train the growth of the plants and to support the plants and the crops they bear, a plurality of upright support structures are typically deployed in parallel in the rows with the plants, the structures supporting a plurality of wires strung from one end of each row to the other. A typical support structure includes a vertical post having one end buried in the ground, and a cross member attached at the other end. The support wires are typically attached to the cross members of the parallel support structures.
Existing trellis structures suffer from a number of common deficiencies including, most notably, the great expense of the support structures themselves, as well as the high cost of installing and maintaining the trellis system in a field. Each support structure includes at least one vertical post, at least one cross member, a means for attaching the cross member to the post, and various means for attaching the plurality of parallel support wires to the cross member(s). Hundreds of each of these parts are required for each acre of ground upon which the trellis system is installed. The installation process is complex, involving precise positioning of the support structures and wires, requiring specially trained and more costly labor for proper installation. After installation, there are continuing costs associated with maintaining and adjusting the tension of the wires and the positions of the support structures on a regular basis, particularly as the weight on the system is increased due to plant growth and the weight of annual crops.
Depending upon the plants to be supported by the trellis structure, it is often desirable to provide support arms that are angled with respect to each other and with respect to the surface of the field, as opposed to flat horizontal arms. By selecting an appropriate angle for the support arms, sunlight and airflow around the plants may be optimized, and harvesting may be simplified. However, such angled support arms are generally formed from inexpensive T-stakes (T-posts) which are notorious for inconsistencies and lack of lateral straightness, resulting in inconsistencies from one support structure to the next in a field. This leads to an inconsistent appearance in the field, potentially inconsistent crop support, and increased maintenance costs.
In addition to being expensive, trellis structures are continuously subjected to the rigors of their outdoor environment. Wind, rain, frost, snow, heat, cold and other environmental factors, as well as such agricultural practices as training, growing, pruning and harvesting performed on the plants all take a toll on the support structures, wires, attachment means, and other parts of the trellis structures. The more elaborate the design of the trellis system, the more significant and expensive these factors can be.
U.S. Pat. No. 5,630,292 describes a trellis structure having a support post that it attached to a cross member that has been bent into a V-shape using a specially designed coupling to form a Y-shaped support. This structure suffers from several drawbacks including significant stress on the central V-bend in the cross member from the great weight of the plants and crops supported. Because of this weight, the single V-shaped member is susceptible to fatigue and early failure. Moreover, the single central attachment coupling between the support post and the V-shaped cross member may act as a pivot, allowing the cross member to move relative to the post, resulting in cross members of adjacent supports to fall out of alignment with each other, thereby requiring frequent adjustments of the structures and the wires they support. The manufacturing of this trellis structure is prone to inconsistent production results that become apparent upon installation in the field, and the installation process itself is inefficient and subject to irregularities and inconsistencies.
It is therefore desirable to provide an inexpensive, durable and reliable trellis support structure for use in commercial agriculture that has minimal susceptibility to failure and that requires a minimal amount of post-installation maintenance. It is also desirable to provide a process for manufacturing trellis structures that provides a consistent end product so that each structure installed in a field has the same desired shape and configuration.